Jet pump refrigeration system



Nov. 10, 1953 E. P. NEUMANN ETAL 2,658,356

JET PUMP REFRIGERATION SYSTEM Filed July 5, 1951 4 Sheets-Sheet 1 Fig. I

IN V EN TOR. M

BY WW Nov. 10, 1953 E. P. NEUMANN ETAL 256515.355

JET PUMP REFRIGERATION SYSTEM FiledJuly 5, 1951 4Sheet s-Sh eet 2 5e 2 62 FROM EVAPORATOR INVENTOR. TO EVAPORATOR w/ 'W WWW ATTORNEYS Nov. 10, 1953 E. P. NEUMANN ETAL JET PUMP REFRIGERATION SYSTEM 4 Sheets-Sheet 5' Fig. 3

\ E OF L //lLl /lllg o l g f7 INVENTOR.

ATTORNEYS Nov. 10, 1953 E. P. NEUMANN ETAL ,658,

JET PUMP REFRIGERATION SYSTEM Filed July 5; 1951 4 Sheets-Sheet 4 LOW TEMP Z 82 f BOX EVAPORATOR CONDENSER I04 CONDENSER if? EVAPORATOR IN V EN TOR.

M ,M,ZKQ#LLY'W ATTORNEYS Patented Nov. 10, 1953 1 JET" PUMP aenmoammon srs'mM Ernest P. Neuman L wem West Boxbury Mass". can n te to Ultra-Mechanisms, Inc., Cambridgegg ass.,- a corporation of Massachusetts Ap li a ion Ju 5, 511 5381 3 .5.32

10 claims, (01; 62-11135 Thisinvention relates. to refrigeration appa ratus' and in particular to systems wherein areirigerant is moved through its cycle by a p es- 1 s rized motive f uid.

,In one aspect the invention comprisesthe combination of an evaporator and a condenser. to- .gether with an improved heat pump including a novel boiler and injector assembly.

a In another aspect theinvention comprises a plurality of jet pump refrigeration systems so coupled as to render it possible to dispose a lowtemperature compartment at any desired zone within a refrigeratedbox.

- An important objectof the invention is toreduce the cost andsimplify thetask of. constructc ingan efficient refrigerator.

.Another. object of the inventi n sto devise a ctwo compartment refrigerator including comvpartments refrigerated to difierent temperature levels and arranged in any one of various rela tive positions.

-still another object of the inventionis to provide a small compact jet pumpretrigeration unit capable of use as a single system or of .being coupled with amultiplicity ofsimilar units to provide flexible. .efllcient refrigeration, at a num- .era t gas coming irom the evaporator.

The second, important, feature of; the intention relat to h provision of means effective t ,causeproper starting of the jet injector forthe boiler feed comprising the combination of. anontrance passage to the boiler controlled by a check valve in combination with atubularcham'bei; between theboiler passage and the jet injector withi hi h t i ia ha e of vapor irom the injector is compressed until the pressure in the chamber is sufiicient to unseat the check valve and thereby start the pressurized f eedingot liquid into the boiler.

Another feature of the invention resides in a system of pressure-operated check valves employed to prevent premature release of vapor from the boiler to the injector and jet pumps.

Another feature of the invention resides in means rendering the system operable with a motive fluid of either greater or lesser specific gravity than the refrigerant fluid.

Still another feature of the invention comprises a combination of motive and refrigerant ciency-of operation of the system.

These and oth r .QbJe JS a t iea ure or the. vention w llhe more re il underst and ..preciated irorntheiohofins detaile esc ntie Lotpreierr d. mb d ments ,thereoi sele te to 5 purpo es ot lus nandshow in heammnanyins drawin s, im Big. 1.15. a view. in. persp ct e 015a ref i erator constructed acco dance. w th th in ent on,

. F s- 2 isa a ammat ie part y n cross- 10. sect on through the. boiler iniestor, and et Pum as em y.

. la. 3 is. a diagrammatic. view =We;Jective otan alternative. embodiment. 1 the nventio and F gi is asl eg am. sehematical y lus ra ing. a double. ni system.

In .advenceoi. a. discussio oi the deta s o1 the .e bo ments,hereinshow t will. be h l iuliir to. consider the g n ral, xsa iz tion. oithe sy to asbest showninFig. 1... 'lhere isprpy de {a .conrentiooal evaporator. 1.0. st ndard enst uction, secur d. to. a pan l H, bathe. ha k of which i se u e; ahofler .lzoi elongat d tubula .ierm- .Tfl ehQflfli 3. se es a r ti P p e5 contained a. housing J4 and co nec ed i geries by apipeJB ha ingcool ng fins J8 secured thereto.- ..Reirie rautsas tromtthe evaporator is pumped andcampressed by theietpumps work- ...mg in. tan em, theemue t there ombeins. e eafter passed through a condenser); which it yie ds heata d i uefiestremth c n enser ZZ .the iimi dr Inseran tog e i h the. mot e flui i t ro t 9 .1 1 mu st ush a tu n i a ent ant! s pa atin eha b rfi As sh w th "po riections are established for operation with V a. heavier retrigerant and a lighter motive fluid. Hence the former collects at the bottom of the separator 46 and is drawn of! through a pipe -28 40.1er dut1 m d e va at r; l -mush a Y MOQM exp n io V The lighter motive fluid fills the upper portion ;of themseparator and is drawn ofithrough an injector contained in e; housingqu and thereby pumpeq back toflthe, boiler -l 2.-- The injector in the housing so is powered by vapor exhausted the boiler '12 and oonduotedto-the injector through anexternal tube. "*Heat for the boiler -is in the form oif Nichrome windings served by a supplyiinefl.

' In operatiomthe liquid refrigerant passes into the evaporator whereit is egg'panded and heated. Fromthe evaporator-the gaseous refrigerant-is drawn by the upper-jet-pump in the housing i4 into-the tube 46 where it is given preliminary compression and wherein part of its heat is exnozzle 66.

3 tracted and radiated to the atmosphere by the cooling fins I8. The partially compressed refrigerant then passes through the tube i6 into the second jet pump into the housing I4 where it is further compressed and then discharged into the condenser 22 where additional heat is given up and wherein the gaseous refrigerant condenses to the liquid state and then passes into the tubular separating chamber 26 where it settles to the bottom readily to pass again through the refrigerating cycle. On the other hand, the motive fluid is withdrawn from the top of the separating chamber 26 by the jet pump in the housing 30, by means of which the liquid is injected into the boiler I2 and therein heated until it vaporizes and leaves the top of the boiler under pressure to serve as the motive fluid for the two stage jet pump. Also a portion of the vapor from the boiler passes through the tube 34 and serves as the motive fluid to operate the injector in the v spiral of Nichrome wire 36, the latter being protected in turn by a casing 4!. There is thus formed an elongated annular chamber 42 lying between the casing 4| and the shell l2. At the bottom of the tube there is disposed a ball check valve 44 serving to prevent the draining of liquid from the bottom of the boiler. At the top of the tube 40 there is a second ball check valve working against a spring 52 set in a socket formed in a plug 48 serving to close the top of the shell l2. Adjacent the upper end of the boiler shell i2 is an outlet 54 which is coupled to an injector nozzle 56 having its inner passage so shaped that vapor leaving the boiler shell I2 first encounters a converging wall portion in which the pressure of the vapor is raised and then a diverging or diffuser portion which discharges into the housing i4. Refrigerant gas is admitted into the housing I4 through a pipe 56 connected into the exhaust end of the evaporator.

. second outlet 62 receiving one end of a bellows connection 64 which is coupled at its outer end to the housing [4 and to a second and smaller jet The condenser tube 22 has an enlarged head projected into the housing [4 (or I4 as shown in Fig. 2) opposite the diiiuser end or I the nozzle 66, the result being that partially comfact, most of the motive fluid will be condensed by the time it reaches the bottom of the housing i4, and I provide a trapped drain 66 leading from the bottom of the housing i4 to the top of the separator 26, the drain 66 having a U-shaped loop portion effective to provide a head of pressure suflicient to prevent liquid in the separator from blowing back into the housing l4 through the drain 66.

Adjacent the upper end 01 the separator there is provided an outlet pipe 10 leading to a housing 30 in which is contained a jet nozzle [2 disposed opposite an injector nozzle 14 leading to a vertical pipe 46 which is connected into the bottom of the tube 40 below the ball check valve 44. Adjacent the bottom of the boiler shell l2 there is provided an annular housing enclosing a conduit 16 leading to a tube 16 which in turn terminates in the nozzle 12.

There are additional factors connected with the operation of the system which require consideration. In order that satisfactory operation may be achieved the nozzle 12 and at least the lower portion of the injector nozzle I4 must be immersed in liquid when the apparatus is started. This is achieved by placing the outlet 10 and the nozzles 12 and 14 substantially below the top of the separator 26, it being understood that both fluids used in the system are liquids at the normal ranges of room temperatures. It is also important that there be liquid in the boiler at the time it is started. This condition is satisfied by the presence of the two ball check valves 44 and 50. The ball check 44 prevents the drainage of liquid from the bottom of the boiler back through the supply tube 46. The function of the ball check 56 is to prevent the escape of vapor from the boiler until a predetermined degree of pressure has been obtained. That is to say, when the current is supplied to the Nichrome windings the liquid in the boiler vaporizes, and the boiler pressure rises until it is sufficient to overcome the compression of the spring 52. Prior to that time no vapor leaves the tube 40. Consequently the injector nozzle 12 is not operating; nor are the jet pumps 56 and 66 operating. However, when the ball check 50 rises due to the pressure in the boiler, the vapor then exhausts through the outlets 64 and 62 to operate the jet pumps 56 and 66 and thereby to start the operation of the refrigeration system. Simultaneously vapor exhausts through the conduit 16 and the tube 18 to the injector nozzle 12 and the motive fluid is then pumped through the tube 46 and into the boiler tube 46 past the ball check 44. If the nozzles 12 and I4 were not immersed in liquid, the rush oi fluid through the nozzle 12 would not be affected to draw motive fluid from the separator 26 and discharge it into the boiler. If there were no liquid in the boiler tube 40 at the start, there would be nothing to start the operation of the nozzles 12, 66 and 66.

It is extremely important to note that the tube 46 interposed between the ball check valve 44 at the entrance to the boiler and the injector nozzle 14 serves as a novel compression chamber eiiective to cause the injector to start feeding the liquid into the boiler without the interposition of auxiliary means to provide starting pressure. If the injector nozzle 14 were coupled directly to the boiler beneath the ball check 44, the initial charge of vapor passing through the nozzle 12 would spend itself vainly against the ball check valve 44 and the access of pressure would blow laterally back through the tube ll] toward the separator 26. However, with the construc- "tion shown in Fig. 2 the-momentumof ;:-the vapor passing through the nozzles .l2 andzil4 ,causes -the stream of vapor to enter the. tube .46 rather than dissipate laterally. During this :process some ofthe vapor is condensed in'the nozzles and in the tube 46, but. the, residual vapor iscompressed within the tube 545 and :as the operation progresses there :is eventually, built in :the tube 146a pressure head'suffic-ient to unseat the :ball

check valve 44 :and start the feedtof liquidinto the bottom of the boilertube-Ml'. It willbe remembered that upon starting the apparatus there .is a quantity of liquid-trapped within the. boiler tube 40. It is importantto note that ,the tube 45 be sufficiently small so that therewill be suffiliquid therein has been completely vaporized.

The size of the tube =45, withsthe foregoing -considerations in mind, is not too. critical and may vary from to Of course, its actual .size will depend upon the relative sizes of the other elements of the system.

Another factor to .be considered is thesdesirability of condensing thegreater partaof vthe motive fluid in the pipe .16 sothat it can drain into the tube 68 and thusreduce the amount of work which has to be .done by the second-jet pump "66.

which is greaterspecific gravity than the motive fluid. Consequently the refrigerant line to the evaporator is taken from the bottom of the separator 26, while the motive-fluid supply-outlet it is connected adjacent theupper end thereof. However, it is equally feasible to employ a motive fluid which is heavier than the refrigerant fluid.

It is merely necessaryto reverse theconnectionsso that the refrigerant supply pipe .25

.is connected adjacent the upper end of the separator andthe supply to the nozzles 12 and I4 .is .connected adjacent the lower end thereof.

Several factors govern the .choice :of. the v.mo-

tive and refrigerant liquids to be used in the system herein disclosed. For example, ,they. must differ in specific gravity inorder to permit. separation either in a centrifugal separator or. in the simple gravity separator shown-inlthedrawings. Obviously they .must be. liquids which do not react chemically with each other and which are I have found, for ex- (C2Cl4). mayadrelatively non-corrosive. ample, that tetrac'hlore'thylene vantageously be used as the motive fluid in combination with methanol (CH4O) as the refrigerant liquid.

With respect to the designof the nozzles preference may be had, in general; to a paper ,on the subject by applicant together w'ith'J. H.

Keenan An Investigation of Ejector'Design by refrigerator design it -has always been regarded "necessary that the freezing orlow "temperature compartment be disposed adjacent the upper end As shown in Fig. 2 the system is connectedfor operation utilizing a refrigerantfiuid of the box. This is "true ibecause'in-thepast {such boxes have. been served by: azasingle-evaporator. Consequently if the evaporator wereflplaced-adjacent thebottom ,of the refrigerated box, :there would be no circulation and theuppenportion thereof would always be at anunduly high temperature. vWhile it would be theoretically ;pos- .sible to; provide two complete-mechanicai-refrigerating systems and thereby achieve freedom of placement for the low temperature compartment, the expense of equipmentrequiredzwould render it uneconomic in almostevervflase. :HDW- ever, one important feature of our inventioniis the fact that a complete -system;involves.-relatively small andinexpensive-equipment or that two complete systems can be applied toone ,re-

,frigerated box without involving uneconomic capital expense. In Figs. 3 and 4 there is illustrated an embodiment .of a double unit comprising another embodiment of the invention. Asshown in Fig. 3 there is provided a la-rge. having an insulated wall within which there is a second and smaller insulated-box :82. .At the front of the box there is a door84 givingaccess to the main box and a door. .83 giving: access to the small box 82. Withinthe smaller boxwor compartment 82 there is disposed a conventional evaporator 88 which is served by a jet pump system secured to theouter surface .oftherear wall of the main box..80. This, system, includes a boiler 96 feeding asingle stage jet pump 82 connected to a tubular condenser 94 which drains into a separator 96 in turn. connected'toanjinjector 98. The parts of the, system have, not been described in detail because they.ar e in,,a'll respects precisely similar tothe corresponding ,elements shown and described in conjunction with Fig. 2, the sole exception being that a single jet pump is served by the boiler insteadjof the duplex arrangement appearing in Fig. ,2.

The condenser 94- is 'in metal to metal contact with a portion of a tubular evaporator 1M mounted within the main box 80 andserved by a two stage jet pump system including a boiler .1112, a first jet pump 1-04 and a second jet pumplOG. .As before, there is provided a separator Ilfl which feeds a jet pump injector MB. Toavoid confusion on the drawing the condenser serving this [second duplex system has been omitted, although the connections for it are indicated. The line H2, for example, brings the condenser into the separator H0. This duplex jet pump system may conveniently be preciselysimilarto the construction shown in Fig. 2. p

The first jet pump system represented by the jet 92 serves to extract heat from then/inner smaller compartment 82, while heat is transferred from its condenser 94 to a portion ofthe large evaporator I00 which in turn is served gby the jet pump system represented ,bythejets I04 and H16. Thus the second system not only. serves to pump heatfrom the condenserof. the'first single stage unit, but alsoextracts, heat fromijthe interior of the main box. Althoughthespecific temperatures maintained in the two compart-, m-ents will be a matter of design and adjustment, it is quite possible, by way of example, to maintain the smaller compartment '82 at a temperature of, say, minus 10 F. while the, interior vof the main box ,8!) is maintained at a temperature of perhaps40 F. I Q

It will be noted that the low temperature compartment 82 is inside by side-relation withthe remaining space within the main boXBO, as opposed. to the conventional arrangement in which the low temperature compartment must of necessity be arranged at the top of the main unit, as in conventional household refrigerators having a compartment for storing frozen foods or making ice cubes. The particular arrangement shown in Fig. 3 is illustrative of the fact that a duplex system constructed in accordance with our invention is flexible with respect to the relative positions of the low temperature compartment and the main box. For example, the low temperature compartment would be placed at the bottom of the main box, at the rear thereof, or in any other desired location. The jet pump systems shown herein are relatively cheap so that a unit having two or more jet pump systems serving various compartments may be constructed at a cost quite competitive with conventional mechanical systems.

While the invention has been herein described in conjunction with a household refrigerator, it

may also conveniently be embodied wherever it is desired to extract heat from a given space and may therefore be usefully employed in conjunction with the air conditioning of railway cars and the like. appreciate that the embodiment herein shown may be modified considerably to fit particular needs.

Having now described a preferred embodiment of the invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigeration system including an evaporator and a condenser, the combination of a shell casing, walls forming a chamber within and spaced from said casing, means for heating said chamber, walls forming a passage from said chamber to the space between the casing and the chamber, a spring-loaded valve normally closing said passage, a pair of jet pumps connected to said casing, a jet injector connected to said casing and to said chamber, a conduit connecting said jet pumps in series, said jet pumps being connected between the evaporator and the condenser, and means for supplying fluid to said injector.

2. In a refrigeration system including an evaporator and a condenser, the combination of a boiler having an inlet for liquid and an exhaust passage for vapor, a jet pump connected between said evaporator and condenser and receiving motive fluid from said exhaust passage, a pressureresponsive check valve controlling said inlet, walls forming a chamber connected at one end to said inlet, a jet pump injector connected to said chamber, a connection from said exhaust passage to said injector, and a source of liquid also connected to said injector, whereby said jet pump injector pumps liquid through said chamber and valve into said boiler.

3. Apparatus of the class described, comprising a boiler having an inlet for liquid and an exhaust passage for vapor, pressure responsive check valves controlling said inlet and said outlet, walls forming a chamber connected at one end to said inlet, a jet pump injector connected to said chamber, a connection from said exhaust passage to said injector, and a source of liquid also connected to said injector.

4. Apparatus of the class described, comprising a boiler having an inlet for liquid and an exhaust passage for vapor, pressure responsive check valves controlling the inlet and the exhaust passage, a pair of jet pumps connected in parallel Those skilled in the art will readily Y to said exhaust passage, a condenser connected to said jet pumps, a tank connected to said condenser, an injector connected to said exhaust passage and to said tank, and walls forming a chamber connected at one end to said boiler inlet and at the other end to said injector.

5. Apparatus of the class described, comprising a boiler having an inlet for liquid and an exhaust passage for vapor, pressure responsive check valves controlling the inlet and the exhaust passage, a pair of jet pumps connected in parallel to said exhaust passage, a condenser connected to said jet pumps, a tank connected to said condenser, a trapped drain connecting said tank to one of said jet pumps, an injector connected to said exhaust passage and to said tank, and walls forming a chamber connected at one end to said boiler inlet and at the other end to said injector.

6. In a refrigeration system including an evaporator and a. condenser, the combination of a pair of jet pumps connected in series between the evaporator and the condenser, a boiler connected to said jet pumps to supply motive fluid thereto, a tank connected to said condenser, an injector connected to receive motive fluid from said boiler, walls forming a compression chamber connected to the discharge end of said injector and to said boiler, a pressure responsive check valve controlling the connection from said chamber to said boiler, and a supply connection from the tank to the injector.

7. A refrigerator comprising a relatively large insulated box, a relatively small insulated box disposed within the larger box, evaporators disposed in both boxes, a first condenser disposed in heat exchange relation with the evaporator in the larger box, a boiler and jet pump assembly unit amounted exteriorly of both boxes and serving to cycle refrigerant through the small box evaporator and the condenser within the larger box, a condenser mounted exteriorly of both boxes, and a second boiler and jet pump assembly mounted exteriorly of both boxes to cycle refrigerant through the evaporator in the larger box and the exteriorly mounted condenser.

8. In a refrigeration system including an evaporator and a condenser, the combination of a shell casing, walls forming a chamber within and spaced from said casing, means for heating said chamber, walls forming a passage from said chamber to the space between the casing and the chamber, a spring-loaded valve normally closing said passage, a jet pump connected to said casing, a jet injector connected to said casing and to said chamber, a conduit connecting said jet pump in series between the evaporator and the condenser, and means for supplying fluid to said injector.

9. Apparatus of the class described, comprising a boiler having an inlet for liquid and an exhaust passage for vapor, pressure responsive check valves controlling the inlet and the exhaust passage, a jet pump connected to said exhaust passage, a condenser connected to said jet pump, a tank connected to said condenser, an injector connected to said exhaust passage and to said tank, and walls forming a chamber connected at one end to said boiler inlet and at the other end to said injector.

10. A refrigerator including a pair of insulated compartments, a first evaporator disposed in the first compartment, a first condenser connected to said first evaporator and disposed in the second compartment, a second evaporator disposed in the second compartment and in heat exchange relation with the first condenser, a sec- References Cited in the file of this patent ond condenser connected to the second evapora- UNITED STATES PATENTS tor and disposed outside both compartments, a first boiler and jet pump disposed outside said Number Name Date compartments and connected to cycle refrigerant 5 214111347 Trumpler 1946 through the first evaporator and first condenser, 2500378 Tobey and a. second boiler and jet pump connected FOREIGN PATENTS cycle refrigerant through said second evaporator Number Country Date and condenser.

ERNEST P. NEUMANN- 10 521,208 Germany Mar. 5, 1931 FERDINAND LUS'I'WERK. 

